1. Field of the Invention
The present invention relates to a device for detecting the angle of incidence of radiation on a radiation incidence surface.
2. Description of Related Art
In a large number of applications, it is convenient to be able to measure the angle of incidence of radiation on a radiation incidence surface by use of measurement technology. Thus, for instance, in the field of air conditioning systems for automobiles, solar sensors are used for detecting the intensity of sunlight incident on the given vehicle and the direction from which the sunlight is incident on the vehicle.
The constructional height of solar sensors for automobiles, i.e. the height by which such sensors extend from the control panel, is normally not negligible. This is perceived of as optically disturbing.
Known from U.S. Pat. No. 5,264,910 and EP-A-0 747 719 A1 are devices for detecting the angle of incidence of radiation wherein a plurality of photodiodes are arranged in a first plane, and a shading mask comprising radiation-transmitting areas and opaque areas is arranged in a second plane above the photodiode. For each pair of photodiodes, the transmitting areas of the shading mask are arranged at a displacement by the same amount. Depending on the angle of incidence of the radiation, a larger or smaller amount of radiation impinges on the photodiodes so that the measuring signal will be a measure for the angle of incidence. Similar devices are also described in U.S. Pat. No. 6,274,862 and U.S. Ser. No. 2002/053,635.
In the known devices, a certain disadvantage is seen in the fact that the angle of incidence has to be detected in an analogous manner, i.e. based on the size of the measurement signal. For the evaluation and subsequent processing of the measuring signal, measurement results in digital form would be considerably more advantageous.
It is an object of the invention to provide a device for detecting the angle of incidence of radiation on a radiation incidence surface wherein the detecting device is of a relatively flat structure and thus is adapted to be integrated into surfaces which can be viewed by the observer.